Drain pump system for laundry machines



Feb. 1 7 1959 Filed Nov. 21, 1956 W. J. RACZYNSKI EI'AL 4 Sheets-Sheet 1 F I6. I

I4 u I5 u- O m 22 l L 1 I |I3 3 INVENTORS WALTER J. RACZYNSKI TOSE-PH C. WORST THEIR ATTORNEY Feb. 17, 1959 Filed Nov. 21, 1956 W. J. RACZYNSKI EI'AL DRAIN PUMP SYSTEM FOR LAUNDRY MACHINES I FIG.2

4 Sheets-Sheet 2 INVENTORS WALTER I RACZYNSKM :rouPH c- WORST THE] R AT TORNIY 1959 w. J. RACZYNSKI ETAL 2,

DRAIN PUMP SYSTEM FOR LAUNDRY MACHINES Filed Nov. 21, 1956 4 Shee 1 a FIG.3

WALTER J'. RACZYNSKI JOSEPH C. WORST THEIR ATTORNEY Feb. 17, 1959 w. J. RACZYNSKI EI'AL 2,373,598

DRAIN PUMP SYSTEM FOR LAUNDRY MACHINES Y Filed Nov. 21, 1956 v 4 Sheets-Sheet 4 FIG.4

INVENTOR.

WALTER :r. RACZYNSKI & :rosaPH c. wons'r F|G.6 BY

THEIR ATTORNEY United States Patent 2,87 3,593 DRAIN PUMP SYSTEM FOR LAUNDRY MACHINES Walter J. Raczynski and Joseph C. Worst, Louisville, Ky., assignors to General Electric Company, a corporation of New York Application November 21, 1956, Serial No. 623,601 7 Claims. (Cl. 68-20) Our invention relates to drain pump systems for use 1n domestic laundry machines and more particularly to such systems for use in combination washer-dryers of the type employing a flow of cold water as the condensing media during the drying operation.

In combination washer-dryers utilizing a cold water condensing action during the drying operation a single drain pump is customarily used during both the washing and drying cycles. During the washing cycle the pump is effective to remove both wash and rinse water from the machine at selected periods, and during the drying cycle it continuously removes the condenser water and condensed moisture from the machine. For reasons of economy a centrifugal type pump with a rotary impeller is ordinarily used since such pumps are considerably cheaper than positive displacement pumps for example, piston type pumps. It is, of course, necessary that the centrifugal pump be capable of removing the Wash and rinsewater Within a certain limited period of time and further it is necessary that the pump maintain the level of the condenser water below a certain maximum point within the machine throughout the drying operation. If the level of water were to rise too high in the tub during the drying operation, it would enter the basket and rewet the clothes which is obviously undesirable.

Although the ordinary centrifugal pump is usually quite satisfactory in removing the wash water from the machine a problem arises when it is used during the drying operation. Specifically, during the drying operation theordinary type of centrifugal pump is quite prone to air locking or binding. In order to meet the drain time requirements of the washing cycle the pump usually has a greater capacity than the how of condenser water admitted to the machine with the result that the inlet to the pump is uncovered at least intermittently throughout the drying cycle. The pump thus draws in air as well as water and as a consequence it often becomes air locked. Air locking or binding can be defined as a total or partial loss or cessation of flow through a pump as a result of the air that is trapped therein, and it means that the pump becomes tot-ally or partially ineffective to drain the liquid from the machine even though its inlet should thereafter become covered with water again. With air trapped in the pump, the discharge pressure of the pump drops so low that the air cannot be delivered or discharged from it against the head or pressure of the water in the discharge piping. Thus the air remains in the pump casing, and little or no water can enter from the pump inlet against the back pressure of the air unless the water in the tub should rise to an undesirably high level. In a combination washer dryer, however, the level within the tub cannot be allowed to reach this high level necessary to re-prime the pump since such a high level would cause wetting of the clothes basket and the clothes being dried. Thus it is necessary that some means he provided in the drain pump system to prevent air locking of the pump.

It is therefore a primary object of our invention to provide a new and improved drain pump system for use in combination washer-dryers in which the centrifugal drain pump is so constructed and arranged within the system that it is not subject to malfunctioning due to air.

locking even though air is drawn into its inlet.

Another object of our invention is to provide a drain pump system for use in combination washer-dryers in which air is exhausted from the centrifugal drain pump whenever itis drawn into the pump casing during the drying operation, to a degree whereby the pump never becomes air locked so as to prevent the flow of liquid therethrough.

In carrying out our invention we provide a washing machine having a liquid containing tub. The tub is drained by. means of a drain pump system. including a centrifugal drain pump which has its inlet connected to the tub and its outlet adapted for connection to a drain. In order to prevent air locking of the pump we provide new and improved bleed means within the drain pump system whereby any air drawn into the pump is bled or exhausted out of it as the pump rotates without there being any spillage of liquid out of the machine. By our invention these means include a bleed opening from the pump and conduit means which are connectedboth to the bleed opening and to the tub. With this arrangement the air drawn into the pump through its inlet is automatically exhausted out of it through the bleed opening and the conduit means so that the pump cannot malfunction due to air locking and there is never any spillage of liquid since any liquid passing through the bleed opening is returned by the conduit means to the tub.

The subject matter which we regard as our invention is particularly pointed out and distinctly claimed in the.

concluding portion of this specification. Our invention, however, both as to organization and method of opera tion, together with further objects and advantages thereof, may best be understood byreference to the following description taken in conjunction with the accompanying drawings in which:

Fig. 1 is a rear elevational view of a combination washer-dryer incorporating a preferred embodiment of our new and improved drain pump system, the view being partially broken away and sectionalized to show details; i

Fig. 2 is a side elevational view of the machine of Fig. 1 with the side panel removed and with certain surfaces broken away to show the drain pump system;

Fig. 3 is a side elevational view of the machine with certain surfaces broken away and partially in section in order to show interior detailsof the machine;

Fig. 4 is a side elevational view of a new and improved drain pump utilized in the drain pump system;

Fig. 5 is a sectional view taken on the line 5-5 of are heated so as to extract moisture therefrom and this moisture is condensed by flowing a sheet of cold condenser water down a wall of the drying chamber. By our invention there is provided Within the machine 1 a new and improveddrain pump system which operates at .selected periods during the washing operation to drain.

the machine of wash and rinse water, and which operates continuously during the drying operation so as to drain the condenser water and the condensed moisture from the machine.

tri-fugal pump 2 which is so constructed and arranged within the system that itdoes not air lock or bind at any patented Feb. 17,

This drain pump system includes a com time, even during the drying cycle when the inlet to the pump may be drawing air. The drain pump system ineluding the construction and arrangement of the pump 2 therein will be described hereinafter in detail.

The machine 1 is of the horizontal axis type, that is, it includes a clothes basket 3 which is rotatable about a generally horizontal axis. The basket 3 is mounted within an outer imperforate tub 4, and the cylindrical side wall of the basket is provided with a plurality of perforations or holes to allow communication between the basket and the chamber 5 defined by the tub. The basket is rotatably supported from the tub 4 by a horizontally extending shaft 6 which is mounted in an elongated bearing 7 (Fig. 3) hung from the rear wall of the tub structure. The shaft 6 as well as supporting the basket 2 also serves to drive it during the operation of the machine. The basket is loaded and unloaded through an opening in the front wall thereof which is aligned with openings in the tub 3 and the outer appearance cabinet 8 of the machine. A hinged door 9 mounted on the appearance cabinet seals around the tub openings so as to close off the chamber 5 during the operation of the machine.

The imperforate tub 4 and the appearance cabinet 8 are both mounted on a suitable base structure 10 at the bottom of the machine. The tub specifically is mounted thereon by means of a plurality of brackets or arms 11 which are secured to upstanding plates 12 fixedly attached on the base. In addition to the tub and the appearance cabinet the base 10 also mounts the basket drive means. The drive means comprises a motor 13 and a multi-speed transmission 14 (see .Fig. l). The motor 13 drives the transmission assembly by 'means of a belt 15 and the transmission assembly in turn drives the basket through a belt v16. The belt '16 specifically turns a basket drive pulley 17 which is mounted on the outer end of the basket drive shaft 6. The transmission assembly 14 is shiftable between two difierent gear ratios so that the basket 2 may be driven at one speed for tumbling clothes and at a second or higher speed for centrifugally extracting water from the clothes. The clothes tumbling speed may, for example, be about 45 R. P. M. and the centrifugal extractions speed about 200 R. P. M. The means whereby the transmission is shifted between the lower and higher speeds preferably comprises a solenoid operated plunger (not shown).

As mentioned above the machine 1 is a combination washer-dryer which proceeds through a cycle of operation first washing and damp drying the clothes and then, if desired, completely or fluff drying the clothes. The clothes basket 3 is driven at its lower .speed both for washing the clothes and for tumbling them during the drying operations. It is driven at its higher speed for extracting water from them by centrifugal extraction. The machine during its sequence of operations is under the control of a cylinder timer sequence control 18 which energizes and de-energizes the various electrical components of the machine in a predetermined sequence. Since the sequence control forms no part of the present invention, it will not be described herein. However, a sequence control and circuit suitable for use in the illustrated machine are described and claimed in the copending application of John W. Toma et al., S. N. 584,658 filed May 14, 1956, now Patent 2,819,540 issued Jan. 14, 1958, and assigned to the same assignee as the present invention.

To heat the clothes during the drying portion of the machine operation and also to heat the wash water during the washing portion of the operation when desired, there is provided in the machine .1 a heater assembly including two heaters 19 and 20. These heaters are mounted within the upper portion of the chamber 5 defined by the tub 4 and they are preferablyof the sheathed type. When they are energized during the washing cycle they beat the water by first heating the basket 2. Then 1 4 as the basket dips into e wash water at the bottom of he tub, it in turn heats the water. In other words, the rotating basket serves as an efiective heat transfer means between the heating element and the water or other washing liquid. When the heaters are energized during the drying cycle, the heat transferred to the basket is then passed on to the elo'thes'to cause vapor migration out of the clothes. Specifically, the heat causes the moisture in the clothes to be evaporated out of them into the air within the chamber 5. cylindrical shell of the basket is perforated, some of the heat from the heaters 19 and 20 passes directly to the clothes by radiation to aid in this moisture removal action.

The valve means whereby wash and rinse water is admitted to the tub 4 during the washing operation of the machine are mounted adjacent the base of the machine (see Figs. 1 and 3). The water supply means includes connections 21 and 22 through which hot and cold water are supplied to the machine respectively. For the washing operation a valve controlled by a solenoid 23 admits hot water to the machine and a valve controlled by a solenoid 24 admits cold water to the machine. The hot and cold water valves under the control of the solenoids 23 and 24 discharge through a common outlet conduit or hose 25. The conduit 25 leads upwardly from the valve means to a point adjacent the top of the ,tub 4 (see Fig. 2) and at its upper end it is connected to an outlet tube 26. The tube 26 as shown discharges the wash and rinse water across an air gap into a funnel .27

mounted on the side wall of the tub. From the funnel 27 the inlet water passes downwardly through a conduit 28 which leads to a sump 29 mounted at the bottom .of the tub. It will be noted that the fill hose 28 includes two separate sections 30 and 31 joined together by a T-connector 32. The purpose of this T-connector and of the third conduit 33 attached thereto will be explained hereinafter. The sump 29 at the lower end of the bottom section 31 of the fill hose is connected to the interior of the tub, i. e. to the chamber '5, by a suitable aperture (not shown) through the bottom of the tub; and when water is supplied to the tub through the fill hose 28., the

water rises upwardly in the tub from the sump thereby filling it. In the illustrated machine a pressure actuated sensing device or water level control 34 (Fig. 1) controls the water inlet solenoids 23 and 24 so as to maintain the proper level in the machine during the washing operation. This sensing device is connected to the interior of the tub 4 by a suitable conduit 35.

The machine 1., as mentioned above, includes a new and improved drain pump system whereby the wash and rinse water is drained from the machine at the close of the washing and rinsing operation. The centrifugal type drain pump .2 of the system is driven at suitable times under the control of the sequence control .18 to effect that result. The drain pump system is also effective to drain the condenser Water and the condensed moisture from the tub 3 during the drying operation, the drain pump 2 being driven continuously during the drying operation. A detailed description of the drain pump system including its method of operation during both the washing operation and the drying operation follows immediately after a brief description of the condenser water inlet means, now to be given.

In the machine .1 the cold condenser water is flowed down a wall of the tub 4 during the drying operation thereby providing a wide cool surface for condensing the moisture extracted from the clothes being tumbled.

The condenser wateris admitted to the machine by means i of a solenoid operated valve which is connected to the inlet water connection water 22 and which is controlled by a solenoid 36 (Fig. l). The solenoid 36 is energized continuously during the drying operation so that the valve controlled by-it passes water at a .slow rate .suf-

ficient to condense the moisture extracted from the.

Since the outer clothes. The condenser .water valve discharges into a separate hose or conduit 37 which leads to. a point adjacent the top of the tub 4 and which there discharges into curved outlet tube 38 (see Fig. 2). The tube 38 in turn discharges into a funnel 39 across a suitable air gap, and the funnel 39 is connected to a line 40 which leads to a vent trap device 41. From the trap device 41 the condenser water then flows through an aperture (not shown) in the tub side wall into the interior chamber 5 of the tub. The trap device 41 is intended to seal off the interior of the tub during the drying operation While venting it through a suitable vent hose 42 during the washing operation. In the illustrated vent trap the flow of condenser water during the drying operation acts as the sealing means, and the arrangement of the trap and in fact the venting system as a whole are described and claimed in the co-pending sole application of Walter J. Raczynski, S. N. 538,891, filed October 5, 1955, now Patent 2,800,008 issued July 23, 1957, and assigned to the same assignee as the present invention. Reference may be had to that application for a full explanation of the operation of the vent trap, the trap forming no portion of the present invention.

The condenser water entering the tub chamber 5 from the vent trap 41 is then flowed down the inner surface of the side wall of the tub in order to condense the moisture being evaporated from theclothes. as a result of the heat supplied from the heaters 19 and 20. Specifically, the water is flowed down the lower quadrant of the tub side wall immediately below the inlet aperture from the vent trap, that is, the lower left hand quadrant of the tub as viewed in Fig. 1. In order to distribute the water evenly across the side wall in a thin sheet there are provided in the machine 1 an inverted V-shaped raised area or chevron 43 on the tub side wall and a water spreader 44 which covers or overlies both the inlet aperture from the vent trap and the upper end of the chevron. The spreader element 44 and the chevron or raised area 43 cooperate so as to spread water across the width of the tub wall whereby it flows down condensing sheet or film.

As the condenser water flows down the wall of the tub it provides a cool surface on which the moisture may condense out of the moist air within the chamber 4. As the moisture condenses it is then carried down the side wall with the condenser water. My invention is particularly directed to a common drain pump system whichis efi'ective to remove this condenser water and condensed moisture continuously during the drying operation and which is also effective to drain the wash and rinse water from the machine during the washing operation. An important advantage of this drain pump system, now to be described, is that means are provided therein for preventing air locking of the centrifugal drain pump 2 during the drying operation or at any other time in which the pump inlet draws in air as well as liquid.

The drain pump system drains the tub 3 through the sump 29 during both the washing and the drying operations. The sump being positioned at the bottom of the tub, the liquid in the tub flows into it by gravity and then is withdrawn from it by means of a conduit 45 which connects the sump to the inlet 46 of the pump. The pump 2 is of the centrifugal type, having a rotary impeller 47 mounted within a pumping chamber 48 formed by easing members 49 and 50 (see Fig. 5), and the inlet 46 enters the pumping chamber through the center region of its one side wall. Specifically, the inlet is in the form of a tube or nipple extending through the center portion of the casing member 50. The impeller 47 which is arranged for rotation on a horizontal axis, includes a disk like base 51 and a plurality of upstanding vanes or blades 52 mounted on the base; and when it is rotated, the direction of rotation being indicated by the arrowin Fig. 4, it discharges the liquid entering'through the inlet 46 into an outlet tube 53, leading from the the wall in a thin.

pumping chamber adjacent the periphery thereof. The outlet is adapted for connection to a drain hose 54, and it will be understood that the hose 54 may be arranged so as to discharge into a set tub or any suitable household Waste pipe.

In the machine 1 the drain pump is driven by means of the main drive motor 13 of the machine. Specifically, the pump shaft 55 on which the impeller 47 is mounted is connected to the drive shaft of the motor by means of a solenoid operated clutch 56 (see Fig. 2). 1 The clutch 56 is driven from the motor by means of a suitable belt drive 57 and it in turn drives the pump shaft through a flexible coupling 58. The clutch is controlled by a suitable solenoid (not shown) so that when the solenoid is energized the clutch is etiective to couple together the motor and the drain pump. Conversely, when the solenoid is tie-energized the motor and the pump are disconnected by the clutch so that the pump remains inoperative. The clutch solenoid is, of course, energized at suitable times during the washing operation so as to drain the wash and rinse water from the machine, and it is energized continuously during the drying operation so as.

to operate the pump for draining the condenser water and condensed moisture from the machine.

In order for the pump 2 to empty the tub within a reasonable time after the Washing operation, it is necessary that it be capable of delivering a greater flow thanis introduced into the tub by the condenser water inlet. means during the drying operation. In other words forv elficient draining of the tub during the Wash cycle, the pump is necessarily capable of pumping faster than the condenser water is admitted during the drying cycle. As a result the pump inlet, that is, the inlet tube 45 from the sump, is not covered with liquid throughout the drying operation. Rather this inlet is uncovered as condenser water trickles into it so that the pump draws,

or sucks in air as well as liquid throughout the drying operation. In order to prevent this air drawn into the pump from air locking or binding it,\we have provided a new and improved means in the drain pump system oreathe to the atmosphere when air is drawn into it without there being any leakage of liquid from the drain.

pump system into the room.

Our new and improved means for preventing air locking of the pump comprise a bleed opening 59 from the pumping chamber 48, which opens through the side wall. of the pumping chamber at a point radially outward of r the inlet 46. Specifically, in the illustrated embodiment the bleed opening or tube 59 is provided in the casing.

member 50 at a point radially outward of the inlet 46 to the pumping chamber. However, with regard to the periphery of the pumping chamber, the bleed opening lies somewhat inwardly of it, that is, closer to the axis of the impeller. With the bleed outlet formed in such a position, that is, outwardly of the inlet to the pumping chamber but inwardly of the periphery of the chamber, a pressure is developed at the bleed opening which is somewhat greater than the pressure at the inlet but which is not as great as the pump discharge pressure at the outlet 53. developed at the bleed opening while the pump is rotating.

The bleed opening 59 in its intermediate pressure location comprises a means whereby air drawn into the pumping chamber may escape from it into the surrounding atmosphere or room without air locking or binding flooding or spillage of liquid in the room, the bleed opening is connected not only to the atmosphere but also to the tub of the machine. Specifically, in the illustrated embodiment the bleed opening is connected In other words an intermediate pressure isto bothathe atmosphere and the tub by means of the fill hose .28. The hose 285s o'fcourseconnectedto the sump 29 and thus to the tub at its lower end, and is open to the atmosphere through funnel '27 at its upper end; and the bleed opening 59 is connected to it intermediate its ends by the conduit or hose 33 and the T-connection32. The connection between the conduit 33 and the fill hose is made, as shown, at a higher level than either the drain pump inlet or the sump.

To explain again the phenomenon of air locking or binding, prior to describing 'how the bleed opening 59 and 'the connected conduits 33 and 28 prevent it from occurring in the pump 2, it will be understood that air locking or binding is created when a centrifugal pump adapted for pumping liquid becomes unable to deliver liquid against the head in its discharge piping due to air drawn into the pumping chamber through its inlet. As a centrifugal pump draws in air rather than being suppliedcompletely with liquid, it builds up a pressurized volume or body or air within the pumping chamber. The liquid already in the chamber and that which may enter with the air passes into a higher pressure annulus around the periphery -of the pumping chamber, but a high enough pressure cannot be developed in the air to keep the fluid annulus at the normal discharge pressure of the pump. Thus the pump becomes ineffective to discharge the liquid through the discharge piping at its normal discharge rate and is spoken of as being partially air locked or bound. If enough air is drawn into the pumping chamber, the pressurized volume of air Within the chamber may reach a size and pressure whereat the pressure of the fluid annulus at the periphery of the chamber is no longer high enough to discharge any liquid through the outlet. The pump is then totally air locked or bound. Once the pump becomes air locked, either partially or totally, the mere presence of the liquid at its inlet is then not enough to cure the air locking by itself. The pressurized volume of air within the pumping chamber creates a back pressure on the inlet whereby the liquid cannot flow into the pumping chamber or will enter only at a reduced rate. Only if a relatively high head of liquid is applied to the inlet is the liquid able to displace the pressurized air within the pumping chamber. In a combination washer-dryer, such as, for example, the illustrated machine 1, the head of liquid at the pump inlet cannot be allowed to build up to that point since it would require a body of liquid within the tub deep enough to cover the bottom of the basket and rewet the clothes. For this reason we provide the means including the bleed outlet 59 and its connected conduits for insuring that the pump 2 cannot become air locked even though it draws in considerable air during the drying operation.

As the pump 2 draws in air through its inlet during the drying cycle, it tends, like a conventional pump, to build up a volume of pressured air within the pumping chamber. The liquid in the chamber passes into an annulus around its periphery but as a result of the bleed opening 59 the volume of air is never allowed to become large enough to cause a serious interruption or reduction in the flow. As the volume of air increases in size its outer edge ultimately reaches the bleed opening 59. There being little or no liquid in the tub at this time, there is thus no head of liquid in the bleed conduit 33 01"1116 fill hose 29, and the high pressure air can escape through the bleed opening 59 and the hoses 33 and .28 to the atmosphere, specifically passing through the upper section 39 of the hose 28. In other words, as the air pressure builds up within the pump, it breathes or puffs to the atmosphere. As the pump so exhausts to the atmosphere, this action reduces the pressure within the pumping chamber so that there .is substantially no back pressure in .thepump inlet conduit 45. In other words a low pressure space is created within the pumping chamber whereby liquid may rflow thereto from the tub- 4, and such ;flow immediately occurs. The result of this exhausting through the opening f5-91is thus that as soon as the pump'tends to become air locked-the air pressure within the pumping dhamber is released and fluid may again enter the chamber. Thereby the pump can at no time become airilodked t-during the drying cycle.

In our improved drain system the lower section 31 of the fill hose 28 performs an important function as well as the upper section 30. It is, of course, through the upper section 30 that the air drawn into the pump is discharged to the atmosphere during the drying cycle. The lower section 310i the hose performs the equally important function of preventingany discharge or spillage of liquid to the room through the bleed means. It will be seen that during the washing operation, depending upon the back pressure or head in the discharge piping which as is well known in the art determines the pressure developed by the pump, the pump 2 may discharge fluid through the bleed outlet 59 and the conduit 33. If the pressure developed at the bleed outlet 59 is great enough the pump will .be able to overcome any head of liquid in the bleed conduit means and discharge liquid into them. It is of course necessary that this liquid flowing through the bleed outlet not be discharged or spilled out into the room, and the section 31 of the fill hose provides a fluid circuit back to the sump 29 and the tub 4 to prevent this. Any liquid flow discharged through the bleed opening 59 and the conduit 33 'is returned by the section 31 of the fill hose to the sump 29 and the tub :4 wherein it is again drawn into the pump inlet. Thus no spillage can occur.

To obtain satisfactory results from our improved drain pump system, it is important that the bleed hole 59 be located properly relative to the central inlet 46 and the peripheral outlet 53 of the pumping chamber. In

a washing machine, it is, of course, necessary that the drain pump system be capable of draining the tub in a suitably short length of time during both the wash and rinse drain periods no matter whether it is operating against a high discharge head or a low discharge head. For example, the drain pump systems of domestic laundry machines are often designed to operate properly against discharge heads ranging anywhere from six feet to no head at all. We have found that by moving the bleed radially outward relative to the impeller axis and the inlet, we increase the time needed'to drain the tub when the pump is working against relatively high discharge heads. .In other words moving the bleed hole 59 radially outward renders the pump less effective to discharge liquid against the high heads. Thus for the best pumping action against high heads the bleed hole should be located as close to the impeller axis as is possible. Conversely, when the bleed hole is moved inwardly the time necessary to drain the tub is increased for low discharge heads. In other words at low discharge heads the pump becomes less effective as the bleed hole is moved closer to the impelleraxis. Thus for the best performance against low heads the bleed hole should be located as far away from the impeller axis as is possible.

Taking into consideration these opposing factors, we

have found that for a satisfactory performance over the range of discharge heads which may be expected in the domestic applications, there is for any particular pump an optimum line of pressure within the pump casing at which the bleedhole should be located. This-pressure'line extends around the impeller axis outwardly of the axis but inwardly of the periphery of the chamber and it lies at somewhat different distances from the axis at various radii from the axis. In other words although the equal pressure line is a closed curve, it is not a true circle. The bleed hole may be located at any point along this pressure line, its location not being limited to any particular point. The location of the pressure line for different pumps may be best determined by experimentation.

To explain briefly why movingathe bleed hole too far outwardly interferes with the pump action and high dis charge heads, and why moving the bleed hole too far inwardly interferes with the pumping action at low discharge heads, as we understand it the reasons for these factors are as follows. When .the pump is pumping against high discharge heads, the impeller creates a high pressure annulus of fluid around the periphery of the chamber. The flow out of the pump is determined by the pressure at the outer edge of this annulus, and that pressure in turn is dependent upon the thickness of the annulus. If the bleed hole is located too far outwardly from the impeller axis, it limits the thickness of the liquid annulus since whenever the inner edge of the annulus begins to cover it, the liquid at the inner edge is discharged out of the pumping chamber through the bleed hole. By thus preventing a thick enough liquid annulus from being formed, the bleed hole prevents the pump from producing the desired flow at high discharge heads if it, the bleed hole, is moved too far outwardly.

Conversely, as mentioned above, the bleed hole must not be moved too far inwardly if a satisfactory flow is to be obtained at low discharge heads. When the pump is working against a high discharge head, it ordinarily produces enough pressure at the bleed hole to cause the bleed flow to pass outwardly to the bleed hole. But when the pump is working against the low discharge heads, it does not produce as great a pressure at the bleed hole and thus depending on the. head applied from the tub through hoses 31 and 33, the flow through the bleed hole may be inwardly rather than outwardly.

The pump may not be able to overcome the head applied from the tub whereby how will occur into the pump through the bleed hole. When liquid flows inwardly into. the ,pumping chamber through the bleed hole, it results in air being drawn into the pumping chamber with it. As the liquid passes from the hose 31 through the T-connector 32 into the hose 33, it draws in air fromrthe hose 30 and carries it into the pumping chamber with it. As a result of this air being so drawn into it through the bleed hole, the pump cannot Work efliciently and hence will not pump out the tub in a satisfactory time. Thus for the best pumping results at low discharge heads it is desirable that the flow be outwardly through the bleed hole. When the flow is outwardly there is no drawing of air into the pumping chamber throughthe bleed hole and thus no loss of pumping efficiency. When the flow is outwardly no air can be drawn into the pumping chamber through the bleed hole since if any air is drawn in through the hose 30 it will be carried by the bleed flow into the sump 29 and the tub 4 rather than into the pumping chamben. Since the direction of the bleed flow at low discharge heads depends upon the pressure developed at the bleed opening or hole, it is therefore desirable forefiicient operation of the pump at the low heads that the bleed be located so that as great a pressure as possible is produced at it. The pressure at the bleed hole depends we have found, upon the distance of the bleed hole from the impeller axis. The greater distance the bleed hole is from the axis, the greater pressure is developed at it and the more likely the flow is to be outward through it. Thus for good pumping efiiciency at low discharge heads, the bleed hole should be as far as possible from the impeller axis. If the bleed hole is too close to the impeller axis, too little pressure is developed at it when the pump is pumping against low discharge heads, so that the bleed flow passes inwardly rather than outwardly and thereby draws in air reducing the pumping etficiency to a considerable degree.

Summing up with regard to the location of the bleed hole, it will be seen that its location is a compromise between two opposite considerations. The bleed hole must belocated, far enough inwardly to allow for satisfactory pumping against high discharge heads, andmust be V10 cated far enough outwardly to allow for satisfactory ump ing at low discharge heads. The optimum location is, as mentioned above, at any point on an equal pressure line around the axis of the impeller.

The point or level at which the bleed conduit 33 is connected to the fill hose 28 is also of importance. To insure that the air exhausted through the bleed opening 59 can rise freely to the atmosphere, the connection to the fill hose should "be located above the level of the bleed hole. If it were located below that level, any liquid in the hose could act as a seal trapping the air and thereby preventing bleeding of the pump. However, at the same time the connection of the bleed line to the fill hose must not be so high above the pump casing as to allow the creation of a pressure head in the bleed line greater than the pressure developed in the pump at the bleed opening during the drying operation. A head in the bleed line greater than the pump pressure at the bleed hole would interfere and possibly even prevent the escape of the air from the pump to the atmosphere. Thus for best results the connection between the bleed line and the fill hose should only be slightly above the level of the bleed outlet. For example, in a size of the illustrated machine suitable for domestic use, having a clothes basket twenty six inches in diameter, it is located only about one inch above the top of the pump casing.

Using the fill hose 28 as a means for connecting the bleed conduit both to the atmosphere and to the tub offers two considerable advantages. First of all, it provides a complete fluid circuit between the pump and the drain sump and tub without any other hoses being required than those already necessary for filling the tub. Secondly, it allows the incoming fill water during the wash and rinse fill operations to purge the bleed line 33 of any foreign material that may have collected in it or at its pump connection. If the bleed line were permitted to clog with foreign material to any extent, it would be inefiective as a breathing means and the pump would be susceptible to air locking. V

In order to obtain the best results from our pumping system, that is, to obtain the best pumping characteristics during the wash drain periods while still preventing.

air locking during the drying operation, we provide within the pumping chamber 48 means whereby the pressure at the bleed outlet is increased over the pressure which normally would be created at that point by the impeller. This results in the pump discharging through the bleed outlet during the wash and rinse drain operations at lower discharge heads than it otherwise would, and thereby prevents the drawing of air into the pump through the bleed at those heads. The tub is thus drained much faster than if the bleed pressure were not increased. The means for increasing the pressure at the bleed outlet comprises a barrier or darn 60 which is positioned behind the bleed outlet (see Figs. 46). By behind the bleed outlet we mean that the dam is positioned downstream of the bleed outlet with regard to the direction of fluid flowpast it toward the pump outlet 53. The dam 60 comprises a projection formed integrally on the inner wall of the casing member 50, which projects into the pumping chamber behind the bleed outlet. The casing member 50 it will be noted is recessed to increasethe width of the pumping chamber, and the dam 60 extends into the chamber for the full depth of this recess. The dam 60 on its leading verter, that is it converts the kinetic energy of the rotating fluid within the pumping chamber to static pressure at the point in the pump casing where the bleed opening opens through the side wall. In other words by the addition of the barrier the pressure at the bleed outlet is increased for the same radial distance ofthe bleed outlet L ees-see '11 from the axis of the impeller. It resultsin the flow through the bleed line being away from the pump during the draining of Wash and rinse water at lower disharge heads than is possible when 'n'o barrier is included in the pumping chamber. An improved pumping performance is thereby obtained since the pump-can thus discharge to lower heads without the efiiciency being reduced by breathing of air from the atmosphere taking place. Thus for the best pump performance for draining wash and rinse water from the tub without interfering in any way with the avoidance of air locking during the drying operation, we prefer to provide a barrier such as the barrier 60 within the pumping chamber.

From the above it will be seen that we have provided a new and improved drain pump system particularly adapted for use in "combination washer-dryers. This drain pump system provides for an effective quick draining of the tub during the washing operation but yet completely avoids air locking of the pump during the drying operation; The air locking of the pump is of course avoided by causing the air within the pump to be exhausted to the surrounding atmosphere, and this release of the air from the pumping chamber is effected without there being any danger of the spilling or discharge of liquid into the surrounding room. By using the fill hose as part of the drain pump system the system is made inexpensive and simple, and additionally the bleed conduit of the pump is cleansed whenever 'wash and rinse water is introduced into the machine. Also, as pointed out above, particularly desirable results. are provided by the provision of the barrier behind the bleed outlet in the pumping chamber. By the provision of the barrier the time required to drain the tub of liquid during the washing operation at the lower discharge heads is substantially reduced without there being any interference whatsoever with the exhausting of trapped air from the pumping chamber during the drying operation.

-While in accordance with the patent statutes we have described What is present is considered to be the preferred embodiment of our invention it will be obvious to those skilled in the art that various changes and modifications may be made therein without departing from the inven- 'tion and it is, therefore, aimed in the appended claims to cover all such variations as fall Within the true spirit and scope of the invention.

What We claim as new and desire to secure by Letters Patent of the United States is:

1. In a washing machine including a liquid containing tub, a centrifugal drain pump for draining liquid from said tub, said pump having an inlet connected to said tub and an outlet adapted for connection to a drain, and means for preventing air locking of said pump comprising a bleed opening from said pump, and conduit means extending at a substantial angle to the horizontal connectcd intermediate its ends to said bleed opening, said conduit means connecting said bleed opening both to said tub at the lower end thereof and to the surrounding atmosphere at the upper end thereof, whereby air-locking of said pump is avoided by the bleeding of air from said pump to said atmosphere without there being any discharge of liquid thereto.

2. In a washing machine including a liquid containing tub, a centrifugal drain pump for draining liquid from said tub, said pump having a generally circular pumping chamber and a rotary impeller disposed within said chamber, and said pump having an inlet to said chamber through a side Wall thereof and an outlet from said chamber at the periphery thereof, a conduit connecting said inlet to said tub and a second conduit for connecting said outlet to a drain, and means for preventing air locking of said pump comprising a bleed opening from said chamber through a side wall thereof, said bleed opening being positioned radially outward of said inlet of said pump and radially inward of said outlet of said pump, and conduit means extending at a substantial angle to the horizontal connected intermediate its ends to said bleed'opening, said conduit means connecting said bleed opening both to said tub at thedo'wer end thereof and to the surrounding atmosphere at the upper end thereof, whereby air locking of said pump is avoided by the bleeding of air from said pump to said atmosphere without there being any dischargeof liquidthereto.

3. In a washing machine including a liquid containing tub, a centrifugal drain pump for draining liquid from said tub, said pump having a generally circular pumping chamber and a rotary impeller disposed within said chamber, and said pump having an inlet to said chamber through a side wall thereof and an outlet from said chamber at the periphery thereof, a conduit connectingsaid inlet to said tub and a second conduit for connecting said outlet to a drain, and means for preventing air locking of said pump comprising a bleed opening from said chamber through a side wall thereof, said bleed opening being positioned radially outward of said inlet of said pump and radially inward of said outlet of said pump, a barrier within said pumping chamber disposed behind said bleed opening for increasing the static pressure head at said bleed opening, and conduit means'extending at a substantial angle to the horizontal connected intermediate its ends to said bleed opening, said conduit means connecting said bleed opening both to said tub at the lower end thereof and to the surrounding atmosphere at the upper ends thereof, thereby to bleed liquid from said bleed opening to the said atmosphere without there'being a discharge of liquid thereto.

4. In a washing machine including a liquid containing tub, a sump formed at the bottom of said tub, "drain outlet means from said sump, a centrifugal drain pump having an inlet connected to said drain outlet means and an outlet adapted for connection to a drain, and means for preventing air locking of said pump comprising a bleed opening from said pump, a bleed conduit connected to said bleed opening, and conduit means extending at a substantial angle to the horizontal connected intermediate its end to said bleed conduit at a higher level than the level of said drain outlet means from said sump and opening at its lower end to said sump and at its upper end to the surrounding atmosphere, thereby to allow for the bleeding of air from said pump without causing discharge of liquid into the atmosphere.

5. In a washing machine including a liquid containing tub, a sump formed at the bottom of said tub, drain outlet means from said sump, a centrifugal drain pump having an inlet connected to said drain outlet means and an outlet adapted for connection to a drain, and means for preventing air locking of said pump comprising a bleed opening from said pump, a barrier within said pumping chamber disposed behind said bleed opening for increasing the static pressure head at said bleed opening, a bleed conduit connected to said bleed opening and conduit means extending at a substantial angle to the horizontal connected intermediate its ends to the other end of said bleed conduit at a higher level than the level of said sump and opening at its lower end to said drain outlet means and at its upper end to the surrounding atmosphere, thereby airlocking of said pump is avoided by the bleeding of air from said pump to said atmosphere without there being any discharge of liquid'thereto.

6. In a combination washer-dryer having an imperferate tub serving as a water container during the washing operation and as a drying chamber during the drying operation, valve means for admitting wash Water to said tub during said washing operation, a fill conduit for receiving said water from said valve means, said fill conduit being connected to said tub adjacent the bottom thereof at its lower end and being open to the atmosphere with its upper end, means including at least one valve for admitting condenser water to said tub during the drying operation of said machine, a centrifugal drain pump for draining water from said tub during both saidwashing operation and said drying operation, said pump having an inlet connected to said tub adjacent the bottom thereof and an outlet adapted for connection to a drain, and means for preventing air locking of said pump comprising a bleed opening from said pump, and conduit means connecting said bleed opening to said fill conduit intermediate the ends of said fill conduit above the level of said pump thereby to connect said bleed opening both to said tub and to the surrounding atmosphere.

7. In a combination washer-dryer having an imperforate tub serving as a water container during the washing operation and as a drying chamber during the drying operation, valve means for admitting wash and rinse water to said tub during the washing operation, a fill conduit for receiving said water from said valve means, a sump connected to said tub at the bottom thereof, said fill conduit being connected to said sump at its lower end and being open to the atmosphere at its upper end, a centrifugal drain pump for draining liquid from said tub, said pump having a generally circular pumping chamber and a rotary impeller disposed within said chamber, and said pump having an inlet to said chamber through a side wall thereof and an outlet from said chamber at the periphery thereof, a conduit connecting said inlet to said sump and a second conduit for connecting said outlet to a drain, means for admitting condenser water to said tub during the drying operation of said machine, and means for preventing air locking of said pump during said drying operation comprising a bleed opening from said pumping chamber through said side wall, said bleed opening being positioned radially outward of said inlet of said pump and radially inward of said outlet of said pump, a barrier within said chamber behind said bleed opening, said barrier extending inwardly from said side wall of said chamber and'being effective to increase the static pressure head at said bleed opening, and conduit means connecting bleed outlet to said fill conduit intermediate the ends of said fill conduit above the level of said pump thereby to connect said bleed outlet both to said tub and to the surrounding atmosphere.

References Cited in the file of this patent UNITED STATES PATENTS 1,345,895 Segvin July 6, 1920 1,983,131 Hume Dec. 4, 1934 1,989,061 Longenecker Jan. 22, 1935 2,217,211 Brady Oct. 8, 1940 2,607,209 Constantine Aug. 19, 1952 

